


A Piece of the Night, and your Heart in my Favour.

by Birdle



Category: Undertale (Video Game)
Genre: F/F, Post-Undertale Pacifist Route
Language: English
Status: Completed
Published: 2018-11-03
Updated: 2018-11-03
Packaged: 2019-08-17 03:09:43
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 3,994
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16508225
Author URL: https://archiveofourown.org/users/Birdle/pseuds/Birdle
Summary: Undyne, now in a long-term relationship with a human, encounters a lover of the past and is intrigued by how it makes her girlfriend feel.(Post-Undertale AU)From my discontinued series 'Gonna See Better Days'. I had started writing several scenarios before stopping, and this is one of them!Again, the title a reference to 'Revolver' by Vian Izak...





	1. Chapter 1

It was supposed to be a normal Saturday evening with a takeaway, cheesy film and just the right amount of bodily contact while sitting shoulder to shoulder on the sofa. But apparently Undyne had other plans. 

I was shrouded in blankets in the living room, and flicking through tv channels until finally deciding on the only monster channel currently available where the very attractive android, Mettaton, was strutting across a game show arena, when she emerged from the bedroom fully clothed in leather jacket, tight leggings and cream turtleneck and began pulling on long crimson leather boots. It had seemed she’d put more effort into her makeup than usual too.

She glanced my way tentatively to see me sprawled comfortably on the sofa,

"I'm just going out to... hang out with Paps! Won't be b-back until later, see ya!!" 

At this point she was at the door and shakily reaching for the doorknob, quite slowly for someone who seemed to be so panicked about leaving. I turned round and glanced at her from my comfortable throne of pillows before turning back,

"Hey, Undyne, where are you actually going?" I tensely asked, eyes still glued to the tv. 

I could see through her lies so easily I wondered why she even tried to pull the 'seeing Papyrus' excuse past me again!

She stopped in her tracks, turning to me with a guilty expression on her face and playing with the bottom of her best leather jacket,

"Well... you see, down in the underworld there was this scientist chick that I had a thing with. About a month after we arrived on the surface I broke up with her. But now she's in town and… wanted to see me? I don't know, I thought I could just go and meet up for a bit to... catch up?" 

She grinned nervously, the beginnings of sweat emerging from her forehead. I was now staring at her in surprise at this long explanation. My mind immediately rushed to the worst case scenario of what could happen if I let Undyne out of my grasp. I had waited too long to have this life of stable relationships and I was not ready to let it go, from her succumbing to an ex! But I reassured myself: she was mine, and I was hers. Nothing would happen. Why don't I trust her? Still, the prickling sense of paranoia made my skin itch with dread.

She, again, stood by the door and turned the handle, but turned to read my expression with a tentative look in her eyes,

"You can come with if you want? The last thing I want you to do is worry, babe!" 

Still sprawled across the sofa in my 'lazy' shirt and surrounded by a multitude of blankets, I chuckled and gestured at myself,

"Should I go like this? Or will you wait for me to get dressed?"

She turned away from the door once more and stretched her mouth into a toothy grin,

"As much as I appreciate your attire, I'm not sure I'd want my ex seeing you like that; wouldn't want her to steal you away from me!"

The heavy atmosphere was dispersed by her relaxed laugh and I smiled at her attempt at comedy. 

I went to pull on a black tank top and skater skirt lying on the floor in a pile of washing, and placed a pair of sunglasses on my head as I walked to stand by her side. I had purposely dressed to compliment her outfit; maybe later I'd 'borrow' Undyne's jacket too to show my property, I pondered. In any case, no ex was going to steal my girl with me around! 

I again struck up a conversation, genuinely curious about Undyne's time in the underworld but I could not get rid of some underlying tones of petty jealousy,

"You've never talked about this ex before! Is she anything special then?"

We left the apartment and she immediately slipped her cool slender hand into mine,

"She was the royal scientist! She did a lot of clever stuff, but she was also a MASSIVE NERD for all things human and had a giant collection of these Japanese books and films... what're they called..."

She stopped in her tracks for a second to think of the names. 

"...Manga and Anime?" I piped up, watching her cutely confused face turn into one of enlightenment,

"Yeah that's the stuff! Anyway..."

We continued chatting about her past lover, and by the sound of things it seemed like this woman was a lizard monster of some sort,

"What's her name, again?" 

"Alphys! Oh yeah, she's also real shy so she probably won't talk to you a lot, just warning ya." 

I nodded understandingly; after all, I wasn't the most talkative person ever either. 

We finally arrived at a small restaurant. It was on the monster side of town and looked nice enough, with potted plants and slightly peeling green paint on the outside. It was very much a generic Italian restaurant. You would see the same decor and experience the same atmosphere in any other non-chain mediterranean restaurant in any other town. Of course, they all have their quirks. That you can't deny. Nevertheless, the interior was plastered in an outdated floral wallpaper which contrasted heavily with the very modern music blasting out of two speakers on either side of the room.

This is what happens when a hip young adult inherits their grandparents’ long-running pizza business. I wonder how it ended up in the monster side of town though? It must've been here long before any monster arrived, and must've been way too stubborn to move and lose the generations of all the same Italian-blooded chefs.

Still holding my hand, Undyne surveyed the area for her friend. After a few seconds, she suddenly clenched her hand which crushed mine, and froze in her step for a second. If I knew my girlfriend, this meant that she was actually more scared than she wanted to let on. Finally, an hoarse "let's go” emanated from her dry lips, which she unconsciously licked in her nervous state. She then muttered something else under her breath, supposedly something in order to motivate herself to go over there. These two hadn't seen each other since they had broken up, after all; there was a lot weighing on this moment. 

 

The palm of her hand became oilier and oilier as she crossed the room. I didn’t know how to feel. Perhaps I should be as scared as Undyne; maybe this ex really is that scary. From the details I’ve heard, she sounds positively contradictory: put on a pedestal for her brains, but also brought down by her apparent shyness. Maybe it wasn't being shy, it was a cunning and quiet intellect? She might be so clever that she has you wrapped round her fingers before you even knew it. 

Preoccupied by this scary inner monologue, I didn't even notice that we had grounded to a halt in front of a small carved mahogany booth with dinky crimson fabric seat coverings and awfully gaudy table decorations. At this table sat a small golden lizard. There was an awkward atmosphere of isolation carried around herself even in such a lively place as this one, probably amounting to the fact that she was alone at the table reading a comic book. 

"H-hey Alphys"

The tiny creature started up, and looked up from the leaves of monochrome pages set out in front of her. Her expression softened for a second after this, before the bulging black eyes (made larger by thick spectacles) darted back and forth to Undyne and I, and also at our entwined hands. She then dropped her book loudly on the scuffed table. 

“Oh! Hello, Undyne! It is great to f-finally see y-you again.”

She gave a frightened glance towards me,

A-and this is…?”

“My girlfriend! She wanted to meet you too so I brought her along.”

The nervous laugh that erupted from Undyne as she scratched the back of her neck was one that I have never heard before. Was I causing more harm by being here? This was probably a bad idea. Curse my paranoia and jealousy. I know it's unreasonable but I can't fight these negative emotions. However, while attempting to shrug off the sinking feeling of being unwanted, I slid into a chair opposite Alphys. Undyne followed suit. 

Before we could even start the small talk, another presence joined us. 

“On behalf of the company I would love to welcome you to 'Ben's Ristorante'. We serve the oldest Italian cuisine in the entire district! What would you lovely ladies like to order?”

A flamboyant waiter stepped close to the table with Italian flag embossed notepad in hand. He seemed extremely uninterested in his job but was attempting to smile and add interesting inflections to his tone of voice so as to not lose his job. 

Undyne, pleased with this distraction from the heavy air, grinned at the adolescent. She didn't even have to glance at the menu to order for the both of us. 

“Just some of number five and eleven for us! What about you, Alphy?”

The nickname sent a shock through my body. I thought about all that time they both had in the underground and how much time exactly they would've been together for. Of course they'd nickname each other, why was I so shocked about all of this? I had been nicknamed and nicknamed people all my life. In any case, it was evident that Alphys was sorely disappointed that Undyne had landed herself a girlfriend so soon. By the look in her eyes I could see that she still had feelings for the siren sitting beside me. Ouch. 

She had been studying the menu for at least half a minute before ordering the first thing on it. In this pause in time, I had a moment to observe the lizard girl for myself. I could see the she was nearly half my height, and was clothed in a spotty black dress. It was a pretty cute getup, to be honest. She definitely was as nervous as Undyne made her out to be, but I could still sense undertones of ulterior motives below the nerd persona. She was a lot cleverer than she let on, even if that intelligence was not as conventional as just science-y stuff. 

After the waiter bowed and wheeled himself off to another table full of rowdy monsters, the small talk could finally begin. I didn't talk much in this conversation. It was interesting to observe the character of these old friends, however. Despite everything I thought, I didn't hate Alphys. She was sweet and nervous and had no ill intention against me, it seemed. She just wanted companionship. I knew too well the feeling of being alone but only wanting the company of those you trust; not any simple company will do. 

The food was brought to us eventually, and besides that the evening continued uneventfully. I even managed to join in the conversation a few times when the topic wasn't way over my head. I couldn't help but slip up once or twice; I really didn't want to seem the controlling partner type, it just sometimes escaped me before I even knew what I was saying. Every time my words seemingly tripped up, I felt Undyne’s steely gaze slide over to meet mine. She knew. 

The sun had completely sank before any of us thought of leaving. Alphys seemed reluctant to move when Undyne and I decided it was late enough to excuse ourselves. I’m sure she didn't want to this confirmation of losing the fish woman completely; while we were in the restaurant it could easily be just the two monsters on a date night, about to go back to a sweet little house to watch meaningless television until the consciousness drained from their minds. Exiting this restaurant solidified the fact that I was indeed going to do those exact things with my girlfriend, and the anxious reptilian was to go back to a one bedroom apartment to watch meaningless television until she could forget this evening ever happened. That gave me a scary sense of power over the situation, that I had got the better end of the stick. Times like these always make me feel as if I am the luckiest woman in the world. 

“Goodbye, Alphy!”

“S-see ya, Undyne. heh.” She wiggled her fingers briefly before scuttering down the pavement and out of sight. 

Time to go home. Snippets of conversation were exchanged but I had a feeling that Undyne was brooding with unknown emotions that could not be expressed in this manner of speaking. It worried me slightly that she was now not talking to me as she would before, but decided not to let it bother me. She had just met an ex she hadn't seen for years!


	2. Chapter 2

**Summary for the Chapter:**

> ohh boii

We finally arrived at our humble abode. Shutting the door softly, Undyne finally voiced her pensive thoughts of the evening:

“You were jealous of her, weren't you?”

Her normal voice had dissipated, leaving a sultry tone infecting her being. Turning to me slowly, she undid her hair and stepped towards me. I had no words. All I could do was take a step back into the arm of the sofa. She was going to play it like this, huh. 

“What a bad girl. I should teach you that you are mine and mine only, and that I am yours.”

The smirk her face formed caused my face to heat up considerably. She knew how to rile me up, and I her. It was my turn to make a move in this chess match of passion. The pawns were up for grabs. 

“I can’t help it. You’re too much in-demand. I could see how your ‘friend’ was staring at you. I can't have that. You’re as much mine as I am yours.”

I mentally apologised to Alphys for making her the villain in this story. Oh well. She took a step forward; I took a step back. She tutted, and replied menacingly,

“Bad, bad girl. Getting jealous over someone I told you not to worry about. Let us get those emotions in check, shall we?”

Before I could fall she gripped my lower back roughly and my leg with another hand and turned a full 180 degrees, pushing me down to deepen the kiss. I was now suspended between her and the floor, feeling her toned hips tight against my soft thigh. This was her exerting her true power. I never felt so vulnerable in my life than in this position. 

Undyne relinquished the spell she had me under and allowed me to make my move.

“You’re the one who’s too goddamn attractive for your own good. Think about that, you siren!” I had never called her that name out loud before and knew it would get a response. There was only a split second to see the tempest of emotion stirring in the backs of her eyes...

...then she dropped me clean onto the ground. I was only suspended a few inches so it was not damaging, but it caused a shock to run down my spine as I observed her emotion-riddled face. It was clear she was more than irritated at my outburst; she was now a primal creature fulfilling her instinct.

This impossible woman pounced over me, our eyes, hers now misted over and tinted red, locking in a deathly stronghold as her nails clasped at my slender, smooth neck. 

“D o n ‘ t t r y m e , h u m a n .”

This out of character remark really set my body into panic mode. It was one thing to play around with Undyne, teasing each other playfully and fully knowing there’s a barrier that must not be crossed, but this storm rose up too quickly and was progressing too fast for me even to realise what truly was going on. I had never seen anything like this of this warrior in all the months I had spent with her. But right now, all I could think, all I could believe was that… 

She really was now a siren. 

And at these terrifying words, she again placed her lips on mine. This time, however, I could feel the force, the urge… the nightmare fuelling it. Because as exciting as this was, it was also taken straight out of my darkest nights where I lay awake for hours contemplating what was out there to hurt me. I was mentally running circles - there was an anxiety deep in the pit of my stomach which bloomed up my throat into something a lot more pleasant. It has always been a fault of mine that actions such as these bring a reaction that is totally adverse to what should be felt. In the wild I would be dead for how often I feel this. 

But I guess I should’ve known; she’s a monster for God’s sake. Some humans are monsters, but all monsters are monsters. And this one was singing sweet melodies straight into my mind but simultaneously had her talons wringing my neck, dragging me down to the depths where roaring waves and chalky cliffs and awful skies were not just figments of the imagination, but hallucinations appearing in front of my eyes. 

And after that kiss broke, she started moving downwards; her jaw unhinged and this siren started biting at the tender skin of my neck. There was not much I could do but close my eyes and bask in the sunlight: hot, burning sunlight stinging my skin with a rash, drawing blood in vampirical ways. 

So I fell into the wavering visage that this mythical creature conjured up, basked in all that it provided but ultimately felt the full tug of the tide dragging me into dangerous waters.

After the dark and heavy atmosphere had dissipated, Undyne finally came back to her senses enough that she could see my ambivalent expression, and with that ceremoniously lifted my aching body and soul to the feather-down of our duvet. It was there, as I lifted my body into a seated position, where she unapologetically cupped her hands around my glowing cheeks.

“Do you want to know why Alphys and I would have never worked out? In a way that cannot be determined or forced at all?”

My eyes widened at this knowledge. There was irresolution in her voice; perhaps this was very personal to her and her ex. I replied simply by giving a startled nod. She continued:

“This is something I have to show you, there is no way I can explain this properly.”

I had never seen such side of this woman, where she was not only sombre in tone but raw in emotion; I’d imagine that the humans who passed through the underground had a glimpse into the unpleasant aura she was suddenly giving off: it seemed as if her warrior side was now fully in function. 

Suddenly, a sharp stinging blossomed around my sternum, and an unpleasant sensation of something attempting to bring my insides to the outside caused me to gasp in pain. This was even more painful than her sharp fangs which had sliced my skin in marks of dominance just minutes earlier. What was this sensation now, however? I had never felt anything like this before, and in my weakened submissive state I did not fight the discomfort. Squeezing my eyes shut when the pain got too much, I heard Undyne cursing under her breath. 

“Shit! I didn’t know it would hurt this much for humans who haven’t been called to fight.”

As she uttered these words, tears began tumbling from the corners of my eyes and fell around my cheeks. Opening my eyes again, I was shocked at the bright light in front of me. At this moment, everything began to click. She was calling out my soul! For what reason?

“Undyne, is this my soul!?” I asked in a weak, whispering voice. 

The fish woman chuckled nervously and spoke in a hushed tone, 

“It should be, but it’s taking it’s goddamn time to get out here! I didn’t think it through and kinda… demanded it to leave your body but obviously human souls are a lot harder to get out, with all that determination and stuff.”

I longed to grip her hands, which were tugging at the materialisations underneath my rib cage, and beg her to stop this torturous pain, but I could barely speak let alone move my limbs. 

Eventually, the pain subsided and I felt a feverish heat spill into my heart, diffusing outwards. Despite it being very warm, it wasn’t uncomfortable anymore. I finally had the courage to look down and view the damage. I had never seen my soul before, never even knew I’d ever see my soul: it was taxing on monsters to attempt to bring out such a core part of a creature, and it was only monsters who had the power to do it. 

In my lover’s hands lay a soft glow of light: it was a deep green, embracing the woody hues of evergreen junipers. It was transcendent. 

She turned the cordate object around in her hands and gazed at the shades it was bouncing on every wall. It began slowly moving away from me and pushed her palms further towards her own body. 

“Wow… I’ve never seen anything like it.”

I was lost for words; she continued,

“Monsters have this thing where if you’re meant to be with your partner, your souls will merge into the same colour pretty quickly. No one in the underground knew if human souls did the same; they’re a lot less compliant to do anything. But now… I’ve got one i n m y h a n d s .”

The scary tone had returned:

“Deep, deep in my soul. There’s a burning feeling I can’t describe. A burning feeling that WON’T let me go until I do this.”

“What!?” I exclaimed, now even more terrified at the vulnerable position I had been put in. 

With almost no coaxing I could see Undyne’s thorax glow just as mine did, and a floating emerald soul to appear. She did not flinch at all but was deep in thought; no words could reach her in this state. I was transfixed by the two glowing orbs between us and without thinking, reached to touch her lighter-coloured, dimmer soul: an actual monster soul. My cold touch on the burning surface of the culmination of life emitted a reaction quite unlike the strong, stern siren: her eyes shut and a tender expression flitted across her face as if my action caused the highest delectation. She gasped for air, 

“Why did you do that?” 

I didn’t withdraw my hand, but caught the vivid thing and brought it nearer my soul. I hadn’t read too much about monster souls in terms of mating, but I recalled that two souls in proximity with each other would show the other what they wanted. 

As soon as they were close enough, the light became shared between the two spirits, merging into one beautiful crystallised mass, coloured colliding and mixing as if it was a giant colour palette. The sensation became more and more intense whilst the heat increased vigorously. Between shallow breaths, the fish monster added further explanation: 

“Alphys’ soul could… never get this far… Besides, hers would… never change colour… and neither would mine… We tried to make it work but… the soul wants what the soul wants.”

This moment was so unique, so special, that neither of us could move for a very long time, until the souls naturally moved away and returned to their rightful places within our chests. 

That night, though I was broken and bruised, was the moment I knew that this woman was my soulmate.

**Author's Note:**

> Heyyy this was a weird idea.... and chapter two, basically a version of thinly veiled smut oops


End file.
